1. Field of the Invention
The present invention relates to a structure of an optical transceiver for performing optical communication. In particular, the present invention relates to a mechanism which releases a lock between a case of the optical transceiver and a cage for accommodating the case.
2. Description of the Related Art
As for a conventional optical module, there is an optical transceiver comprising a light-emitting element and a light-sensitive element for performing communication by means of an optical fiber and performing photoelectric conversion. This kind of optical transceiver has an optical unit including the light-emitting element and light-sensitive element built into a case, and this case is detachably inserted into a cage provided on a board such as printed circuit board (PCB). An electrical connector connected to the board is provided in the cage. If the case of the optical transceiver is inserted in the cage, a joining terminal of the optical transceiver is connected to the electrical connector provided in the cage. The optical transceiver converts an electrical signal received from the board to an optical signal and sends it to the optical fiber and also converts the optical signal received from the optical fiber to the electrical signal and outputs it to the board. Thus, the optical transceiver converts the optical signal and electrical signal mutually so as to allow optical communication.
The optical transceiver detachably inserted in the cage must be securely fixed in the cage. This is because, if the optical transceiver comes off the cage during operation, not only the communication is disrupted but a communication apparatus including the optical transceiver may also break down. For this reason, the case for this kind of optical transceiver has a lock mechanism for locking it in the cage.
As for the optical transceiver detachable from the cage, compatibility was required among products of various manufacturers so that the optical transceiver can be replaced easily with a spare optical transceiver if it breaks down. If the products of the manufacturers are compatible, therefore the user can procure the spare parts easily and inexpensively from abundant alternatives without being limited to the products of a specific manufacturer.
Consequently, to establish the compatibility among the optical transceivers provided from the manufacturers, an industry standards body established a standard called Multi Source Agreement (MSA) regarding a Small Form-factor Pluggable (SFP) transceiver as a kind of optical transceiver. The MSA standard prescribes forms and dimensions as to the SFP transceiver and the cage for inserting the SFP transceiver therein. According to the MSA standard, a projecting lock portion is provided on a bottom face of the SFP transceiver, and a plate spring portion having a locking hole for locking the lock portion formed thereon is provided on the cage. Therefore, if the SFP transceiver is inserted in the cage, the lock portion of the SFP transceiver is locked in the locking hole provided on the cage so as to lock the SFP transceiver in the cage.
When pulling the SFP transceiver out of the cage, means for releasing the lock is necessary. A method of releasing the lock between the optical transceiver and the cage is disclosed in U.S. Pat. No. 6,439,918. This will be described by using FIGS. 1 and 2.
FIG. 1 is a sectional side view of a conventional transceiver locked in the cage. In FIG. 1, a lock member 1104 provided to a case 1101 has a lock portion 1104a locked in a locking hole 1110a formed on a cage 1110, and is swingable centering on a spindle 1105. If the user turns a lever 1103 on a rotary axis 1103a in an arrow direction, the lock member 1104 coupled to the lever 1103 swings centering on the spindle 1105 so that the lock portion 1104a goes up. The lock portion 1104a comes off the locking hole 110a of the cage 1110 so as to release the lock between the optical transceiver and the cage. FIG. 2 shows a state in which the lock between the optical transceiver and the cage is released. In FIG. 2, if the user pulls the lever 1103 in the arrow direction, the case 1101 of the optical transceiver is detached from the cage 1110.
FIGS. 3A and 3B show an example of mounting multiple optical transceivers in the communication apparatus. Such an example of mounting was developed while almost all the apparatuses including the communication apparatuses were miniaturized and the optical transceivers provided in the communication apparatuses were also miniaturized and rendered high-density in recent years.
FIG. 3A is a perspective view showing a part of a conventional communication apparatus on which multiple optical transceivers are mountable. In FIG. 3A, multiple cages 1110 for mounting the optical transceivers are provided for the sake of allowing the multiple optical transceivers to be provided being mutually adjacent on the left, right, top and bottom in the communication apparatus. There are also multiple boards 1120 piled up vertically for mounting the multiple cages 1110. An opening of each cage 1110 is aligned with a slot 1130a provided on a panel 1130, and the case 1101 of the optical transceiver is inserted in the cage 1110 through the slot 1130a. 
FIG. 3B shows a state in which the multiple optical transceivers are mounted on the communication apparatus of FIG. 3A. In FIG. 3B, the user cannot insert his or her finger between an upper optical transceiver and a lower optical transceiver vertically and adjacently placed. Therefore, the user cannot place his or her finger on the lever 1103 of the optical transceiver and pull it forward. It is not possible, however, to mount the optical transceivers at a high density in the communication apparatus if they are arranged to allow the user to place his or her finger between the upper and lower optical transceivers.
Incidentally, Other mechanisms for releasing the lock will be described by using FIGS. 4A to 5.
FIGS. 4A and 4B are a partially sectional view and a perspective view showing a connector-detachable mechanism disclosed in Japanese Utility Model Laid-Open No. 1-162945 respectively. FIG. 4A shows a state in which a case 2001 is accommodated in a mounting hardware 2004.
If the user turns a handle 2002 and pulls it to the front of the case 2001 from the state of FIG. 4A, the case 2001 is pulled out of the mounting hardware 2004, and a first connector 2005 is set apart from a second connector 2006. FIG. 4B shows this state.
FIG. 5 is a perspective view showing the lock mechanism of an electronic device disclosed in Japanese Utility Model Laid-Open No. 2-10153. An electronic device 3001 is an in-car electronic device such as a car stereo, which is locked onto a vehicle body not shown.
In FIG. 5, if the user pushes a lock release button 3002, the lock of the electronic device 3001 onto the vehicle body is released, and a handle pressing lever 3023 turns centering on a support 3024 so that a press portion 3023a pushes out a handle 3012 to the front of the electronic device 3001. If the user pulls the pushed-out handle 3012, the electronic device 3001 is pulled out of the vehicle body.